Allegro MicroSystems expands three-phase sensorless BLDC gate driver portfolio

Allegro MicroSystems has expanded its portfolio of three-phase sensorless BLDC gate drivers.

Its newest offerings, the A89332 and A89332-1, are designed to meet the evolving needs of cooling systems in data centres offering flexible options for designers.

Available with integrated power loss brake (A89332) and AC-loss (A89332-1) features, these drivers enable compact, high-airflow fan designs to improve thermal efficiency, reducing energy use and data centre costs.

When server fans malfunction or break, backflow causes them to go into reverse rotation. The other fans have to work harder to compensate for the resulting airflow, which increases power consumption. The traditional solution to preventing reverse rotation is adding external circuitry and components to function as the power loss brake - components that do not fit into 1U fans. This approach requires software coding, increases bill of material (BoM) size, and increases time to market.

Addressing these pain points, the A89332’s integrated power loss brake (PLB) function applies a brake to fans that aren’t working properly and stops them from spinning, with braking performance that’s four times better than discrete implementations. This eliminates unnecessary power consumption and increases thermal efficiency, ultimately reducing data centre costs.

When combined with the A89332-1’s AC loss logic, Allegro is now able to serve the high-end server market with gate drivers offered in a 4 mm x4 mm QFN package that’s 36% smaller than comparable options - suitable for “donut” circuit boards.

Allegro offers the industry’s only code-free solutions for server cooling fans; the company’s embedded algorithms and graphical user interface (GUI) eliminate the need for an additional Hall-effect position sensor and motor control unit (MCU), and no additional software development is required. This helps system designers reduce R&D overhead, simplify motor tuning, and improve time to market.

The reduced need for external components further helps optimise system cost and improve reliability, and integrated functionality gives customers increased flexibility when faced with tight design requirements.

Both devices are available in a 26-contact 4mm × 4mm QFN package with exposed thermal pad (suffix EX). These packages are lead (Pb) free, with 100% matt-tin lead frame plating.